The invention relates to a memory device for a rail longitudinal guide for a motor vehicle seat.
A memory device of this kind is provided for use in a rail longitudinal guide which has two longitudinally extended guide rails which are displaceable relative to each other in the extension direction in order to be able to adjust the longitudinal seat position of a motor vehicle seat. For this one of the two guide rails is mounted fixed on the body on the vehicle floor of a motor vehicle and the second guide rail which is displaceable relative thereto serves as the seat rail for holding a motor vehicle seat. By moving the second rail relative to the first rail which is fixed on the bodywork it is thus possible to set the longitudinal seat position of a motor vehicle seat mounted on the second guide rail in the rail longitudinal direction. Rail longitudinal guides of this kind are normally mounted in pairs on the two longitudinal sides of a motor vehicle seat.
In order to be able to find again the previous seat longitudinal position as quickly as possible and without difficulty after a change in the longitudinal position of a motor vehicle seat it is known to equip the rail longitudinal guide with a memory device by which certain seat longitudinal positions can be stored as so-called memory positions. For this the memory device comprises a first memory module which is mounted displaceable on one of the two guide rails, more particularly the guide rail fixed on the bodywork, along the extension direction thereof in order to be able to set a specific memory position by moving the first memory module. Furthermore a locking device is provided on the first memory module for locking a previously set memory position. This first memory module on the one guide rail is assigned a second memory module on the other second guide rail (more particularly the seat rail) which is mounted locally fixed there—relative to the rail longitudinal direction—and has a stop which on reaching a seat longitudinal position of the second guide rail corresponding to the memory position enters into engagement with a counter stop of the first memory module.
In other words, a movement of the first memory module along a first of the two guide rails (namely the guide rail fixed on the bodywork) permits a choice of a certain memory position which is fixable by a locking device of the first memory module. This memory position corresponds to a certain seat longitudinal position, i.e. a certain position of the two guide rails relative to each other (in the rail longitudinal direction); and this memory position can be found in that a second memory module provided on the second guide rail (seat rail) has a stop which on reaching the memory position enters into engagement with the associated counter stop of the first memory module.
An important useful field for memory devices of this kind are motor vehicle seats having a so-called easy-entry function (climb-in aid). Motor vehicle seats with easy entry function can be moved forwards from an actual set seat longitudinal position with the backrest folded forwards in order to facilitate entry into the corresponding vehicle behind the vehicle seat which has been pushed forwards. Equipping a vehicle seat with an easy entry function is standard in front seats of two-door motor vehicles.
The memory device serves in the case of a motor vehicle seat having easy-entry function to immediately find without problem when sliding back the vehicle seat the seat longitudinal position previously set before moving the vehicle seat forwards with backrest folded forwards which can be for example the preferred seat longitudinal position of the driver.
A motor vehicle seat of this kind known from German Patent Application No. 101 27 152 A1 comprises                a seat frame        a backrest which is mounted for pivotal movement on the seat frame and which can be folded forwards from its useful position in the direction of a seat surface of the seat frame,        a rail longitudinal guide with which the seat frame can be moved to adjust the seat longitudinal position in the seat longitudinal direction,        a fixing device for locking the seat frame in a previously set seat longitudinal position,        an actuating element for releasing the fixing device so that the seat frame can be moved in the seat longitudinal direction,        a coupling mechanism which acts on the actuating element and which unlocks the fixing device when the backrest is folded forwards towards the seat surface,        a memory device by which the seat frame during movement in the seat longitudinal direction can be stopped automatically in an adjustable seat longitudinal position defined as the memory position,        a locking device of the memory device for locking a set memory position as well as        means through which the locking device is coupled to the backrest.        
By coupling the locking device of the memory device to the backrest it is to be achieved that when moving the vehicle seat with the backrest raised up into a new seat longitudinal position a new memory position can also be set whereas during sliding the vehicle seat with the backrest folded forwards which serves to execute a so-called easy entry function the previous memory position is to remain for a rapid return.
The object of the present invention is to improve a memory device for a motor vehicle seat of the type mentioned at the beginning.